I have done an upgrade from Umbraco 7.1.8 to 7.4.1 (which was a really painful process). As part of this upgrade, we needed to update Contour to Forms. I followed the following process from another post...

1. Duplicate Datbase
2. Remove Contour (uninstalled it)
3. Installed Forms
4. Installed Migration Tool
5. Ran the Migration Tool

When checking the forms (which were incorrect - for some reason it duplicated the forms) NO records were ported across. This i can live with (but is annoying). The main problem i have is the Entries form does not work. I keep getting the following error message. Anyone else had this issue? If so, how/what caused it.

I do have the Diplo Date Range Picker installed (which is required for the site) and a few other packages (most of the main ones people use).

TypeError: Cannot read property '_weekdaysMin' of undefined
at new DateRangePicker (http://cse.local/App_Plugins/UmbracoForms/Assets/daterangepicker/daterangepicker.js?cdv=1168013063:45:39)
at HTMLDivElement.<anonymous> (http://cse.local/App_Plugins/UmbracoForms/Assets/daterangepicker/daterangepicker.js?cdv=1168013063:871:44)
at Function.x.extend.each (http://cse.local/umbraco/lib/jquery/jquery.min.js?cdv=1168013063:4:4575)
at x.fn.x.each (http://cse.local/umbraco/lib/jquery/jquery.min.js?cdv=1168013063:4:1626)
at $.fn.daterangepicker (http://cse.local/App_Plugins/UmbracoForms/Assets/daterangepicker/daterangepicker.js?cdv=1168013063:868:14)
at HTMLDocument.<anonymous> (http://cse.local/App_Plugins/UmbracoForms/js/umbraco.forms.js?cdv=1168013063:1725:25)
at l (http://cse.local/umbraco/lib/jquery/jquery.min.js?cdv=1168013063:4:24882)
at Object.c.add [as done] (http://cse.local/umbraco/lib/jquery/jquery.min.js?cdv=1168013063:4:25192)
at x.fn.x.ready (http://cse.local/umbraco/lib/jquery/jquery.min.js?cdv=1168013063:4:1685)
at x.fn.x.init (http://cse.local/umbraco/lib/jquery/jquery.min.js?cdv=1168013063:4:1243) <div ng-model="filter" umb-forms-date-range-picker="" class="date-filter pull-left ng-isolate-scope ng-scope ng-pristine ng-valid">

Personally, i think the whole upgrade process should be investigated and streamlined. Spending 2 full working days to do a simple upgrade is unrealistic.